This invention relates generally to an apparatus for detecting particles in a fluid medium and, more particularly, to an apparatus and method for detecting the presence of metallic particles in a fluid medium and transmitting data relating to the particle accumulation to a remote receiver.
Mechanical systems such as engines and transmissions utilize a lubricating oil or other fluid to dissipate heat within the system and to reduce wear on system components. However, due to the nature of the systems, wear does occur, resulting in the presence of small metallic particles in the oil or other lubricating fluid.
Due to the normal wear and the natural breakdown of the oil or other lubricating fluid, the lubricating fluid in such systems must be changed periodically. This is typically done on a time or usage basis, for example, every 90 days or 2000 hours of use. While small metal particles may result from normal wear, larger particles are usually an indication of abnormal wear or a more serious problem. For example, the resulting wear creates abnormal amounts of metal particles within the lubricant. Under normal maintenance procedures, the metal particles would be present in the lubricant for an extended period of time. If this condition is not identified and the appropriate repairs completed, more expensive repairs including the replacement of major system components may result.
Detection of metallic particles in hydraulic systems is equally important as hydraulic systems represent large expenses in the event of component failure. If failures are detected early, repair expenses can be minimized; however, if catastrophic failure occurs, the large amounts of particles caused by the failure can enter the hydraulic system and cause damage to many other components. Fortunately, any catastrophic failure of one of the components is often preceded by the gradual breakup of one or more components. If this breakup can be detected, corrective action can be taken before any further damage to surrounding components occurs.
In U.S. Pat. No. 5,502,378 assigned to the assignee of the present application, a sensor is disclosed that detects particles within a fluid that is generally comprised of a housing defining a cavity and a magnet disposed adjacent to the cavity bottom to attract particles into the cavity. A first coil is wound about the surface of the cavity. The induction of the first coil is responsive to the particle accumulation within the cavity. A second coil is wound about the magnet. The induction of the second coil is responsive to the temperature of the fluid and is independent of the particle accumulation within the cavity. In this system, electrical wiring connects the sensor to remote displays or alarms located in the operator compartment. In mechanical systems such as engines, transmissions, differentials, torque converters, oil and hydraulic systems, and other similar systems associated with work machines such as earth moving equipment, articulated trucks and so forth the wiring connecting the sensor to the warning or monitoring system may be subject and/or exposed to weather, extreme temperatures, and physical damage.
It would therefore be desirable if there were provided a fluid particle sensor that would transmit sensor data to the operator compartment or to a remote location without using conventional wiring for traversing the entire distance between the sensor and the monitoring or warning system; that would provide easier maintenance and installation; and that would provide trend data on the life of a particular machine system.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the present invention, a sensor for detecting particles in a fluid is generally comprised of a housing which houses the various components of the sensor, a battery for supplying power to such components, a microprocessor for processing incoming and outgoing signals, an rf transmitter for converting electrical signals into rf signals, and a first rf antenna for transmitting the processed signals to a remote location. The present sensor has a specific identification code associated therewith to identify and distinguish the signals outputted from such sensor. The identification code could also be tied to the particular type of equipment such as a particular work machine.
The sensor housing further includes a cavity having a magnet disposed adjacent to the cavity bottom to attract particles into the cavity. A first coil is wound around the outer surface of the cavity. The induction of the first coil is responsive to the particle accumulation within the cavity. A second coil is likewise wound about the outer surface of the cavity and is spaced from the first coil. The induction of the second coil is responsive to the temperature of the fluid and is independent of the particle accumulation within the cavity.
A second rf antenna and receiver positioned at a remote location receives the transmitted rf signals and decodes and processes such signals back into electrical signals indicative of the particle accumulation within the cavity for inputting into a second microprocessor or electronic controller. The second microprocessor stores and monitors the particle information generated by the present sensor and such information may be used for trend or component failure analysis. This particle information may also be inputted into a machine information monitoring system via a signal outputted by the second microprocessor, the monitoring system producing a warning signal in response thereto if such signal exceeds a predetermined value.